Request routing utilizing point of presence load information

ABSTRACT

A system, method and computer-readable medium for request routing based on prioritization and load information are provided. A client request processing a resource identifier for requested content transmits a DNS query to a content delivery network service provider. Based on a content provider identifier included in the DNS query, a receiving DNS nameserver determines a selection from a hierarchical organization of POPs and the relative capacity for a selected POP to process a subsequent request for resources. Based on the processing of the prioritization information and load information, the receiving DNS nameserver resolves the DNS query.

BACKGROUND

Generally described, computing devices and communication networks can be utilized to exchange information. In a common application, a computing device can request content from another computing device via the communication network. For example, a user at a personal computing device can utilize a software browser application to request a Web page from a server computing device via the Internet. In such embodiments, the user computing device can be referred to as a client computing device and the server computing device can be referred to as a content provider.

Content providers are generally motivated to provide requested content to client computing devices often with consideration of efficient transmission of the requested content to the client computing device or consideration of a cost associated with the transmission of the content. For larger scale implementations, a content provider may receive content requests from a high volume of client computing devices which can place a strain on the content provider's computing resources. Additionally, the content requested by the client computing devices may have a number of components, which can further place additional strain on the content provider's computing resources.

Some content providers attempt to facilitate the delivery of requested content, such as Web pages or resources identified in Web pages, through the utilization of a content delivery network (“CDN”) service provider. A CDN service provider typically maintains a number of computing devices, generally referred to as “points of presence” or “POPs” in a communication network. The service provider POPs can include one or more domain name service (“DNS”) computing devices that can process DNS queries from client computing devices. Additionally, the POPs can include network resource storage component that maintain content from various content providers. In turn, content providers can instruct, or otherwise suggest to, client computing devices to request some, or all, of a content provider's content from the CDN service provider's computing devices. Upon receipt of resource requests from such client computing devices, a CDN service provider typically delivers the requested resource in accordance with terms (such via a service plan) specified between a corresponding content provider and the CDN service provider.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a block diagram illustrative of content delivery environment including a number of client computing devices, content provider, and a content delivery network service provider;

FIG. 2 is a block diagram of the content delivery environment of FIG. 1 illustrating the registration of a content provider with a content delivery service provider;

FIG. 3 is a block diagram of the content delivery environment of FIG. 1 illustrating the generation and processing of a content request from a client computing device to a content provider;

FIG. 4 is a block diagram of the content delivery environment of FIG. 1 illustrating the generation and processing of a DNS query corresponding to an embedded resource from a client computing device to a content delivery network service provider;

FIG. 5 is a block diagram of the content delivery environment of FIG. 1 illustrating the generation and processing of embedded resource requests from a client computing device to a content delivery network service provider; and

FIG. 6 is a flow diagram illustrative of a request routing routine implemented by a content delivery network service provider utilizing prioritization and load information associated with the processing of a resource request.

DETAILED DESCRIPTION

Generally described, the present disclosure is directed to routing of DNS queries from client computing device corresponding to content requests for a network resource. Illustratively, the processing DNS queries are received by a service provider, such as content delivery network (“CDN”) service providers, that has one or more computing devices for processing the DNS queries. The processing of a DNS query by a CDN service provider is generally referred to as request routing.

Specifically, aspects of the disclosure will be described with regard to the processing of a client computing device DNS query within a content delivery network service provider domain as a function of prioritization information selected by a content provider related to the processing of the content requests received from the client computing device and. Additionally, aspects of the disclosure will be described with regard to the further processing of selected prioritization information with utilization load and health information attributed to one or more points of presence (“POP”) associated with a service provider providing requested resources on behalf of the content provider.

In one embodiment, a CDN service provider, or other service provider, receives DNS queries from client computing devices. In the DNS portion of the URL, the CDN service provider utilizes a content provider identifier to determine prioritization information that includes a selection from two or more tiers of POPs that may be utilized to provide requested resources. In one embodiment, each tier may be associated with a financial cost incurred by the content provider based on the CDN service provider providing resources from POPs associated with the selected tier. The CDN service provider can then obtain or request availability information for at least a portion of the POPs utilized by the CDN service provider, such as the POPs that are associated with the selected tier. Illustratively, availability information can include information associated with load information associated with the processing of content requests by the POP. Additionally, availability information can include health information associated with whether one or more computing components or computing resources associated with a POP is functionality properly.

The CDN service provider can then utilize the availability information to determine whether POPs associated with the selected tier has sufficient capacity to process a subsequent resource request. If so, the CDN service provider can resolve the DNS query by identifying one or more POPs associated with selected tier in a response to the client computing device. The CDN service provider also utilize other request routing information, such as latency information, CDN service provider costs, etc. in selecting from various POPs in a selected tier. Alternatively, if POPs associated with the selected tier do not have sufficient capacity, the CDN service provider can mitigate by identifying alternative POPs.

Although various aspects of the disclosure will be described with regard to illustrative examples and embodiments, one skilled in the art will appreciate that the disclosed embodiments and examples should not be construed as limiting. For example, although aspects of the disclosure will be described with regard to specific service providers such as a CDN service provider, one skilled in the relevant art will appreciate that aspects of the disclosure may be implemented by various types of service providers or that a service provider implementing aspects of the disclosure is not required to have the specific components utilized in the illustrative examples.

FIG. 1 is a block diagram illustrative of content delivery environment 100 for the management and processing of content requests. As illustrated in FIG. 1, the content delivery environment 100 includes a number of client computing devices 102 (generally referred to as clients) for requesting content from a content provider, a CDN service provider, or other service provider. In an illustrative embodiment, the client computing devices 102 can corresponds to a wide variety of computing devices including personal computing devices, laptop computing devices, hand-held computing devices, terminal computing devices, mobile devices, wireless devices, various electronic devices and appliances and the like. In an illustrative embodiment, the client computing devices 102 include necessary hardware and software components for establishing communications over a communication network 108, such as a wide area network or local area network. For example, the client computing devices 102 may be equipped with networking equipment and browser software applications that facilitate communications via the Internet or an intranet.

Although not illustrated in FIG. 1, each client computing device 102 utilizes some type of local DNS resolver component, such as a DNS nameserver, that generates the DNS queries attributed to the client computing device. In one embodiment, the local DNS resolver component may be provide by an enterprise network to which the client computing device 102 belongs. In another embodiment, the local DNS resolver component may be provided by an Internet Service Provider (ISP) that provides the communication network connection to the client computing device 102.

The content delivery environment 100 can also include a content provider 104 in communication with the one or more client computing devices 102 via the communication network 108. The content provider 104 illustrated in FIG. 1 corresponds to a logical association of one or more computing devices associated with a content provider. Specifically, the content provider 104 can include a web server component 110 corresponding to one or more server computing devices for obtaining and processing requests for content (such as Web pages) from the client computing devices 102. The content provider 104 can further include an origin server component 112 and associated storage component 114 corresponding to one or more computing devices for obtaining and processing requests for network resources from the CDN service provider. One skilled in the relevant art will appreciate that the content provider 104 can be associated with various additional computing resources, such additional computing devices for administration of content and resources, DNS nameservers, and the like. For example, although not illustrated in FIG. 1, the content provider 104 can be associated with one or more DNS nameserver components that receive DNS queries associated with the domain of the content provider 104 and that would be authoritative to resolve client computing device DNS queries corresponding to a domain of the content provider (e.g., return an IP address responsive to the DNS query). A DNS nameserver component is considered to be authoritative to a DNS query if the DNS nameserver can completely resolve the query by providing a responsive IP address.

With continued reference to FIG. 1, the content delivery environment 100 can further include a CDN service provider 106 in communication with the one or more client computing devices 102 and the content providers 104 via the communication network 108. The CDN service provider 106 illustrated in FIG. 1 corresponds to a logical association of one or more computing devices associated with a CDN service provider. Specifically, the CDN service provider 106 can include a number of Point of Presence (“POP”) locations 116, 122, 128 that correspond to nodes on the communication network 108. Each POP 116, 122, 128 includes a DNS component 118, 124, 130 made up of a number of DNS nameserver computing devices for resolving DNS queries from the client computers 102. Each POP 116, 122, 128 also includes a resource cache component 120, 126, 132 made up of a number of cache server computing devices for storing resources from content providers and transmitting various requested resources to various client computers. In some embodiment, the CDN service provider may maintain one or more request routing services 134 for processing DNS queries independent of the POPs associated with the CDN service provider 106.

Still further, the CDN service provider 106 includes a prioritization information data store 136 for maintaining information regarding prioritization profiles or configurations specified by various content providers 104. The prioritization information data store 136 can also maintain information associated with a selection by the content provider 104 of preferences for providing requested resources for each of the POPs 116, 122, 128. In an illustrative embodiment, the prioritization information data store 136 corresponds to a central data store accessible by the POPs 116, 122, 128, such as via a Web service. In another embodiment, each POP 116, 122, 128 can maintain a local version of a prioritization information data store 136 for utilization in request routing as will be explained in greater detail. Additionally, although the prioritization information data store 136 is illustrated as a single data store, one skilled in the relevant art will appreciate that the prioritization information data store 136 may correspond to one or more data stores and may be implemented in a distributed manner.

The DNS components 118, 124 and 130 and the resource cache components 120, 126 132 may further include additional software or hardware components that facilitate communications including, but not limited, load balancing or load sharing software/hardware components.

In an illustrative embodiment, the DNS component 118, 124, 130 and resource cache component 120, 126, 132 are considered to be logically grouped, regardless of whether the components, or portions of the components, are physically separate. Additionally, although the POPs 116, 122, 128 are illustrated in FIG. 1 as logically associated with the CDN Provider 106, the POPs will be geographically distributed throughout the communication network 108 in a manner to best serve various demographics of client computing devices 102. Additionally, one skilled in the relevant art will appreciate that the CDN service provider 106 can be associated with various additional computing resources, such additional computing devices for administration of content and resources, and the like.

With reference now to FIGS. 2-5, the interaction between various components of the content delivery environment 100 of FIG. 1 will be illustrated. For purposes of the example, however, the illustration has been simplified such that many of the components utilized to facilitate communications are not shown. One skilled in the relevant art will appreciate that such components can be utilized and that additional interactions would accordingly occur without departing from the spirit and scope of the present disclosure.

With reference to FIG. 2, an illustrative interaction for registration of a content provider 104 with the CDN service provider 106 will be described. As illustrated in FIG. 2, the CDN content registration process begins with registration of the content provider 104 with the CDN service provider 106. In an illustrative embodiment, the content provider 104 utilizes a registration application program interface (“API”) to register with the CDN service provider 106 such that the CDN service provider 106 can provide content on behalf of the content provider 104. The registration API includes the identification of the origin server 112 of the content provider 104 that will provide requested resources to the CDN service provider 106. Additionally, as will be explained in greater detail below, the content provider 104 can also provide prioritization information or prioritization criteria utilized by the CDN service provider 106 to route content requests.

In one embodiment, the prioritization information can include the selection of one or more tiers of POPs utilized by the CDN service provider 106 to provide requested content (hosted on behalf of the content provider 104). Each tier may be associated with a financial cost incurred by the content provider 104 based on the CDN service provider 106 providing resources from a POP associated with a selected tier. As will be explained in greater detail below, the prioritization information is associated with a customer identifier or content provider identifier that is included in resource identifiers. In other embodiments, the prioritization information can include one or more identifiers that specify a specific tier without identifying the content provider 104. In another embodiment, the prioritization information can include a specification of a maximum financial cost that the content provider is willing to incur for all content provided by CDN service provider 106 (e.g., a maximum financial amount per month).

In other embodiments, the prioritization information can also include additional information utilized by the CDN service provider 106 or other service provider in processing DNS queries. In one aspect, the prioritization information can include a determination of an average size load associated with the requested content (e.g., size of file). The average size load can be approximated according to one or more predefined classes (e.g., large, medium, small, etc.). The average size load can also be very specific in terms of an actual measurement of load size over a period of time. The average load size may be attributed to all requests made by client computing devices 102 to a content provider 104 (e.g., an average load size attributable to the content provider). The average load size may also be attributed to requests made by specific client computing devices 102 or groupings of client computing devices (e.g., an average load size attributable to particular DNS resolver component). Illustratively, load size may be defined in a variety of ways including, but not limited to, a size of file, time required to process a result, a cost attributed by the CDN service provider, and the like. In still another embodiment, the prioritization information can include the specification of service level information (e.g., a desired average latency) or other criteria that may be utilized in the request routing process.

One skilled in the relevant art will appreciate that upon identification of appropriate origin servers 112 (or other origin source utilized by the content provider), the content provider 104 can begin to direct requests for content from client computing devices 102 to the CDN service provider 106. Specifically, in accordance with DNS routing principles, client computing device requests corresponding to a resource identifier provided by the content provider 104, but identifying a domain associated with the CDN service provider 106 would eventually be directed toward a POP 116, 122, 128 associated with the CDN service provider. In the event that the resource cache component 120, 126, 132 of a selected POP does not have a copy of a resource requested by a client computing device 102, the resource cache component will request the resource from the origin server 112 previously registered by the content provider 104.

With continued reference to FIG. 2, upon receiving the registration API, the CDN service provider 106 obtains and processes the registration information. In an illustrative embodiment, the CDN service provider 106 can then generate one or more content provider identifiers that will be transmitted by the client computing devices 102 as part of the DNS queries preceding content requests. Illustratively, the content provider identifiers may be unique identifiers associated with a single content provider 104. Alternatively, the content provider identifier may be unique identifiers associated with groupings or sets of content providers 104. One skilled in the relevant art will appreciate that various types of additional information may be generated by the CDN service provider 106 and that the additional information may be embodied in any one of a variety of formats.

The CDN service provider 106 returns an identification of applicable domains for the CDN service provider (unless it has been previously provided) and any additional information to the content provider 104. In turn, the content provider 104 can then process the stored content with content provider specific information. In one example, as illustrated in FIG. 2, the content provider 104 translates resource identifiers originally directed toward a domain of the origin server 112 to a domain corresponding to the CDN service provider. The translation of resource identifiers to identify a domain of the CDN service provider 106 can be generally referred to as a “modified URL.” The general translation of resource identifiers will be described below.

Generally, the identification of the resources originally directed to the content provider 104 will be in the form of a resource identifier that can be processed by the client computing device 102, such as through a browser software application. In an illustrative embodiment, the resource identifiers can be in the form of a uniform resource locator (“URL”). Because the resource identifiers are included in the requested content directed to the content provided, the resource identifiers can be referred to generally as the “content provider URL.” For purposes of an illustrative example, the content provider URL can identify a domain of the content provider 104 (e.g., contentprovider.com), a name of the resource to be requested (e.g., “resource.xxx”) and a path where the resource will be found (e.g., “path”). In this illustrative example, the content provider URL has the form of:

-   -   http://www.contentprovider.com/path/resource.xxx

During an illustrative translation process discussed above, the content provider URL is modified such that requests for the resources associated with the modified URLs resolve to a POP associated with the CDN service provider 106. In one embodiment, the modified URL identifies the domain of the CDN service provider 106 (e.g., “cdnprovider.com”), the same name of the resource to be requested (e.g., “resource.xxx”) and the same path where the resource will be found (e.g., “path”). Additionally, the modified URL can include various additional pieces of information utilized by the CDN service provider 106 during the request routing process. Specifically, in an illustrative embodiment, the modified URL can include data indicative of content provider identifier that allows for the association of prioritization information specified by the content provider 104. Alternatively, the modified URL can also include the prioritization directly in the modified URL. In this embodiment, the modified URL would have the form of:

-   -   http://content_provider_identifier.cdnprovider.com/path/resource.xxx

Additionally, the modified URL can include any additional information utilized by the CDN service provider during the request routing information, including, but not limited to, service plan information, file identifiers, and the like. The modified URL would have the form of:

-   -   http://additional_information.content_provider_identifier.cdnprovider.com/path/resource.xxx

In another embodiment, the information associated with the CDN service provider 106 is included the modified URL, such as through prepending or other techniques, such that the modified URL can maintain all of the information associated with the original URL. In this embodiment, the modified URL would have the form of:

-   -   http://additional_information.content_provider_identifier.cdnprovider.com/www.contentprovider.com/path/resource.xxx

In both of the above examples, the content provider identifier and additional information are separated as separate labels in the modified URL. One skilled in the relevant art will appreciate that the cost information and any additional information can be combined together in a single label of the modified URL. Generally, the content provider identifier and additional information may be considered to be in the portion of the URL accessible to a DNS nameserver in DNS query processing.

Illustratively, the modified URLs are embedded into requested content in a manner such that DNS queries for the modified URLs will resolve to a DNS sever corresponding to the CDN service provider 106 and not a DNS nameserver corresponding to the content provider 104. Although the translation process is illustrated in FIG. 2, in some embodiments, the translation process may be omitted in a manner described in greater detail below.

With reference now to FIG. 3, after completion of the registration and translation processes illustrated in FIG. 2, a client computing device 102 subsequently generates a content request that is received and processed by the content provider 104, such as through the Web server 110. In accordance with an illustrative embodiment, the request for content can be in accordance with common network protocols, such as the hypertext transfer protocol (“HTTP”). Upon receipt of the content request, the content provider 104 identifies the appropriate responsive content. In an illustrative embodiment, the requested content can correspond to a Web page that is displayed on the client computing device 102 via the processing of information, such as hypertext markup language (“HTML”), extensible markup language (“XML”), and the like. The requested content can also include a number of embedded resource identifiers, described above, that corresponds to resource objects that should be obtained by the client computing device 102 as part of the processing of the requested content. The embedded resource identifiers will generally in the form of the modified URLs, described above.

Alternatively, the embedded resource identifiers can remain in the form of the content provider URLs that would be received and processed by a DNS nameserver associated with the content provider 104. In this alternative embodiment, the receiving DNS nameserver would use a canonical name record (“CNAME”) that would identify the network storage component 110. Upon receipt of the returned CNAME, the client computing device 102 subsequently transmits a DNS query corresponding to the received CNAME. The client computing device 102 can then process the received CNAME in a manner similar to the modified URLs, described below. For ease of illustration, however, the alternative embodiment will not be described in further detail and the additional processing steps will only be described with regard to the modified URL. One skilled in the relevant will appreciate that the below description may be applicable to CNAMEs as described in the alternative embodiment.

Upon receipt of the requested content, the client computing device 102, such as through a browser software application, begins processing any of the markup code included in the content and attempts to acquire the resources identified by the embedded resource identifiers. Accordingly, the first step in acquiring the content correspond to the issuance, by the client computing device 102 (through its local DNS resolver), a DNS query for the modified URL resource identifier that results in the identification of a DNS nameserver authoritative to the “.” and the “com” portions of the modified URL. After partially resolving the “.” and “com” portions of the embedded URL, the client computing device 102 then issues another DNS query for the resource URL that results in the identification of a DNS nameserver authoritative to the “.cdnprovider” portion of the embedded URL. The issuance of DNS queries corresponding to the “.” and the “com” portions of a URL are well known and have not been illustrated.

With reference now to FIG. 4, in an illustrative embodiment, the successful resolution of the “cdnprovider” portion of the original URL identifies a network address, such as an IP address, of a DNS nameserver associated with the CDN service provider 106. In one embodiment, the IP address is a specific network address unique to a DNS nameserver component of a POP. In another embodiment, the IP address can be shared by one or more POPs. In this embodiment, a further DNS query to the shared IP address utilizes a one-to-many network routing schema, such as anycast, such a specific POP will receive the request as a function of network topology. For example, in an anycast implementation, a DNS query issued by a client computing device 102 to a shared IP address will arrive at a DNS nameserver component logically having the shortest network topology distance, often referred to as network hops, from the client computing device. The network topology distance does not necessarily correspond to geographic distance. However, in some embodiments, the network topology distance can be inferred to be the shortest network distance between a client computing device 102 and a POP. In still further embodiments, a request routing service 134 associated with one or more DNS nameservers may also receive the request.

With continued reference to FIG. 4, in either of the above identified embodiments (or any other embodiment), a specific DNS nameserver in the DNS component 118 of a POP 116 illustratively receives the DNS query corresponding to the original URL from the client computing device 102. Once one of the DNS nameservers in the DNS component 118 receives the request, the specific DNS nameserver attempts to resolve the request. In an illustrative embodiment, a specific DNS nameserver can resolve the DNS query by identifying one or more IP addresses of cache server components that can process a subsequent request for the requested resource. Illustratively, the resolution of the DNS query will be based, at least in part, on the prioritization information and availability information of POPs. As described above, a selected resource cache component can process the request by either providing the requested resource if it is available or attempt to obtain the requested resource from another source, such as a peer cache server computing device or the origin server 112 of the content provider 104.

As an alternative to selecting a cache server component, the CDN service provider 106 can maintain sets of various alternative resource identifiers. The alternative resource identifiers can be provided by the CDN service provider 106 to the client computing device 102 such that a subsequent DNS query on the alternative resource identifier will resolve to a different DNS nameserver component within the CDN service provider's network. In an illustrative embodiment, the alternative resource identifiers are in the form of one or more CNAME records. In one embodiment, each CNAME record identifies a domain of the CDN service provider 106 (e.g., “cdnprovider.com” or “cdnprovider-1.com”). As will be explained in greater detail below, the domain in the CNAME does not need to be the same domain found in original URL or in a previous CNAME record. In a manner similar to the information described above, each CNAME record includes additional information utilized by a receiving DNS nameserver for processing the DNS query. In an illustrative embodiment, the additional information can include cost information corresponding to information or criteria utilized by the CDN service provider 106 during the request routing process. The cost information included in the CNAME can be the same cost information provided in the modified URL or additional/alternative costs information obtained by the CDN service provider 106. Additionally, in embodiments in which cost information is not provided in the modified URL, the cost information would corresponding to cost information obtained by the CDN service provider 106 (directly or indirectly). As also described above, the CNAME can also include additional request routing information, (e.g., “request routing information”) utilized by the CDN service provider 106. An illustrative CNAME record can have the form of:

-   -   http://content_provider.identifier.cdnprovider.com/path/resources.xxx     -   CNAME     -   request_routing_information.content_provider_identifier.cdnprovider.com

In an illustrative embodiment, the CNAME records are generated and provided by the DNS nameservers to direct a more appropriate DNS nameserver of the CDN service provider 106. As used in accordance with the present disclosure, appropriateness can be defined in any manner by the CDN service provider 106 for a variety of purposes.

In an illustrative embodiment, the CDN service provider 106 will utilize the prioritization information, at least in part, to identify the more appropriate DNS nameserver of the CDN service provider 106. As previously mentioned, in one embodiment, the prioritization information corresponds to a selection of one or more tiers of POPs. Each tier is includes two or more POPs and is generally associated with different financial cost parameters incurred by the content providers 104. In one example, each tier can be associated with a different region of the world in which POPs are located (e.g., North America, Asia, Europe, etc.). In another example, each tier can be associated with selected POPs that may have similar capacities or that host similar content on behalf of content providers irrespective of geographic location (e.g., a tier that includes United States west coast POPs and Asia, a tier that includes United states Midwest, and a tier that include United States east coast and Europe). In still another example, each tier can be associated with POPs that have similar network characteristics or network performance (e.g., tiers defined in terms of average latencies or based on logical network mapping information).

In one embodiment, the tiers can be hierarchically arranged such that a selection of a tier higher in the hierarchy also includes all the underlying tiers as well. Such tiers may be referred to as “overlapping” or “complimentary.” For example, a selection of a first tier level may relate to selection between a Seattle POP, a San Francisco POP or a Portland POP. A second tier level may include a selection between West Coast POPs, Midwest POPs and East Coast POPs. In the second tier, as selection of West Coast POPs would include a selection of the Seattle POP, the San Francisco POP and the Portland POP. In another embodiment, the tiers may be exclusionary of each other such that there is no overlap in POPs between tiers.

As described above, in addition to the consideration of prioritization information, the CDN service provider 106 can utilize the additional information (e.g., the “additional information”) included in the modified URL to select a more appropriate POP. In one aspect, the CDN service provider 106 can utilize the additional information to select from a set of DNS nameservers identified as satisfying criteria specified in the prioritization information. For example, the additional information can correspond to network identification information or other information that can be used to attribute a geographic location to the client computing device 102 (or associated DNS resolver component). In another aspect, the CDN service provider 106 can utilize the additional information to validate the POP selected in accordance with the cost information or to select an alternative DNS nameserver previously selected in accordance with the cost information. In still another aspect, the CDN service provider 106 can utilize the additional information to select a set of potentially applicable POPs (e.g., meeting minimum service levels or satisfying specific security parameters) and then utilize the cost information to prioritize from the set of potentially applicable POPs.

In accordance with one embodiment, each DNS nameserver may be associated with a data store or have access to a data store that defines CNAME records for various URLs. If a DNS query corresponding to a particular URL matches an entry in the data store, the DNS nameserver component 118 returns a CNAME record as defined in the data store. In an illustrative embodiment, the data store can include multiple CNAME records corresponding to a particular original URL. The multiple CNAME records would define a set of potential candidates that can be returned to the client computing device. In such an embodiment, the DNS nameserver component 118, either directly or via a network-based service, can implement additional logic in selecting an appropriate CNAME from a set of possible of CNAMEs. In an illustrative embodiment, each DNS nameserver component 118, 124, 130 maintains the same data stores that define CNAME records, which can be managed centrally by the CDN service provider 106. Alternatively, each DNS nameserver component 118, 124, 130 can have a POP specific data stores that define CNAME records, which can be managed centrally by the CDN service provider 106 or locally at the POP 116, 122, 128.

The returned CNAME can also include request routing information that is different from or in addition to the information provided in URL/CNAME of the current DNS query. For example, if the CNAME selection is based on regional plan, a specific regional plan can be identified in the “request_routing_information” portion of the specific CNAME record. A similar approach could be taken to identify service level plans and file management by including a specific identifier in the “request_routing_information” portion of the CNAME record. In another embodiment, request routing information can be found in the identification of a CDN service provider 106 domain different from the domain found in the current URL/CNAME. For example, if the CNAME is based on regional plan, a specific regional plan domain (e.g., “cdnprovder-region1.com”) could be used in the domain name portion of the specific CNAME record. Any additional request routing information can be prepended to the existing request routing information in the current URL/CNAME such that the previous request routing information would not be lost (e.g., serviceplan.regionalplan.cdnprovider.com). One skilled in the relevant art will appreciate that additional or alternative techniques and/or combination of techniques may be used to include the additional request routing information in the CNAME record that is selected by the DNS nameserver component 118.

One skilled in the relevant art DNS nameserver component 118 may select (or otherwise obtain) a CNAME record that is intended resolve to a more appropriate DNS nameserver of the CDN service provider 106. In may be possible, however, that the same DNS nameserver would also be authoritative for the subsequent DNS query for the CNAME to be provided to the client computing device. For example, a specific DNS nameserver may be authoritative for a both a specific regional plan and a service level plan. Thus, returning a CNAME would still result in the DNS query arriving at the same DNS query (may be due in part to the client computing device's geography). In such an embodiment, the DNS nameserver, such as DNS nameserver component 118, may choose to resolve the future DNS query in advance.

With continued reference to FIG. 4, upon receipt of the DNS query related to the modified URL or the DNS query related to a CNAME, the received DNS nameserver processes the DNS query to attempt to resolve the DNS query. Illustratively, the resolution of a DNS query relates to the identification of one or more network addresses (e.g., IP addresses) corresponding to resource cache components that may be able to process requests for resources (e.g., HTTP GET requests). More specifically, upon receipt of the DNS query, the receiving DNS nameserver component obtains the content provider identifier included or references in the DNS portion of the modified URL. Based on the content provider identifier, the receiving DNS nameserver (or other service provider component) obtains the prioritization information specified by or otherwise associated with the content provider 104. Based on prioritization information, the DNS nameserver can identify one or more POPs that are included in one or more tiers. The DNS nameserver may maintain the tier information locally. Alternatively, the receiving DNS nameserver can obtain at least a portion of the prioritization information from a service component or a peer device.

In addition to the utilization of the prioritization information associated with the content provider, the receiving DNS nameserver also obtains or determines the availability of POPs satisfying the selected tier. Illustratively, availability can generally refer to the likelihood that an identified resource cache component and other associated resources would be available for subsequent content requests transmitted by client computing devices. Accordingly, availability may be defined in terms of the number of requests the POP is able to handle (e.g., load) and whether the resource cache components are functioning properly (e.g., POP health). The subsequent content requests would be in response to the DNS query resolution transmitted to the request client computing device 102.

Illustratively, the determination of the likelihood that a subsequent resource request can be processed can be based on capacity information corresponding to an estimated number of requests that the identified resource cache components may be capable of processing or anticipated to be processing at the time the subsequent resource request is transmitted/received. In one example, the estimated number of requests can be based on historical information provided by the POPs to a management component, such as a DNS request routing service 136, indicative of the number of requests that were capable of being processed. Alternatively, the historical information can also include information indicating a threshold number of requests that was exceeded and that produced errors or deficiencies in performance. In another example, the estimated number of requests can be based on the above historical capacity information further organized by time-based criteria, such as time of day. In a further example, the estimated number of request can be based on real-time or substantially real-time reporting of capacity/load. The estimated number of request can further be based on time windows, such as hourly peak capacity, and the like.

Based on the prioritization information, the availability information and any additional information, the receiving DNS nameserver processes the information to select which POPs will be identified in response to the DNS query. In one example, the DNS nameserver may attempt to try and identify only POPs that are not only associated with a selected and applicable tier, but in which the availability information is indicative that the identified POP (or components thereof) can process subsequent requests for the identified resource (e.g., remaining within acceptable performance thresholds). The receiving DNS nameserver can utilize additional information, such as average size of a request or designation of the size request to determine whether a potentially selected POP has sufficient capacity. For example, if the modified URL includes a designation of size or reference to size in the modified URL, the receiving DNS nameserver may be able to extract the sizing information from the additional information in the modified URL.

Still further, the receiving DNS nameserver can then utilize additional selection criteria to further prioritize or refine from potential POPs. For example, the receiving DNS nameserver can determine or obtain latency information related to an identified client computing device 102 (or corresponding DNS resolver component). In another example, the receiving DNS nameserver can associate a cost defined in terms of CDN server provider resources consumed and then select or prioritize POPs based on a minimization of the attributable CDN service provider costs. One skilled in the relevant art will appreciate that the processing of the prioritization and load information may incorporate additional information not discussed above.

With reference now to FIG. 5, in an illustrative example, assume that the DNS nameserver component 130 has selected the resource cache component 132 of POP 128. Upon receipt of the IP address for the resource cache component 132, the client computing device 102 transmits requests for the requested content to the resource cache component 132. The resource cache component 132 processes the request in a manner described above and the requested content is transmitted to the client computing device 102.

With reference now to FIG. 6, a request routine 600 implemented by the CDN provider 106 will be described. One skilled in the relevant art will appreciate that actions/steps outlined for routine 600 may be implemented by one or many computing devices/components that are associated with the CDN service provider 106. Accordingly, routine 600 has been logically associated as being performed by the CDN service provider 106.

At block 602, one of the DNS nameserver components 118, 124, 130, 136 obtains a DNS query corresponding to resource identifier (the “receiving DNS nameserver”). As previously discussed, the resource identifier can be a URL, such as the modified URL, that has been embedded in content requested by the client computing device 102 and previously provided by the content provider 104. Alternatively, the resource identifier can also correspond to a CNAME provided by a content provider DNS nameserver in response to a DNS query previously received from the client computing device 102.

At block 604, the receiving DNS nameserver obtains content provider identifier information and other additional information to be utilized in the request routing process. Illustratively, the content provider identifier information and at least a portion of the additional information may be included in the DNS portion of the modified URL (or other identifier). Additionally, some portion of the additional information, such as a client computing device identifiers (or DNS resolver) may be included or derived from the DNS query as well. For example, the DNS query can include a network address as part of the request protocol. The network address can be attributed to specific client computing devices 102 or DNS resolvers.

At block 606, the receiving DNS nameserver obtains prioritization information associated with the content provider identifier. In one embodiment, the receiving DNS nameserver obtains the prioritization information by referencing the content provider identifier with information maintained at the POP or in a central repository. In another embodiment, the receiving DNS nameserver obtains some portion of the prioritization information directly from the modified URL associated with the DNS query. As previously described, illustratively, the prioritization information may include the identification of one or more tiers. In another embodiment, the prioritization information may include the ad hoc selection of specific POPs.

At block 608, the receiving DNS nameserver obtains availability information for one or more POPs or tiers of POPs. As previously discussed, the processing of the availability information can generally refer to a determination of whether an identified resource cache component and other associated resources would be available for subsequent content requests transmitted by client computing devices. The additional content requests would be in response to the DNS query resolution transmitted to the request client computing device 102. Such a likelihood determination can be based on an estimated number of requests that the identified resource cache components may be processing or anticipated to be processing. In one example, the estimated number of requests can be based on historical information provided by the POPs to a management component, such as a DNS request routing service 136. In another example, the estimated number of requests can be based on the above historical information further organized by time-based criteria, such as time of day. In a further example, the estimated number of request can be based on real-time or substantially real-time reporting of capacity/load. The estimated number of request can be based on time windows, such as hourly peak capacity, and the like.

At block 610, the receiving DNS nameserver processes the availability information to determine the likelihood the one or more POPs in a selected tier have capability to process a subsequent request for content. As previously described, in one aspect, the processing of availability information may relate to a determination of a maximum number of requests that can be processed by a POP and a determination whether processing the subsequent request will cause the POP to exceed a maximum threshold. In another aspect, the processing of load information may relate to a determination of an average size of request associated with the content provider and a determination of whether processing subsequent requests of the size associated with the content provider with exceed a maximum threshold. The processing of load information can also include the evaluation of other criteria used to sort the load information, such as time of day or other time-based criteria. Additionally, in another embodiment, the processing of the availability information may include a determination of an average request associated with a particular client computing device 102 or grouping of client computing devices (e.g., by DNS resolver or Internet Service Provider (“ISP”)).

At block 612, the receiving DNS nameserver selects one or more POPs in the selected tiers and in which there is not a likelihood for an identified POP to exceed a maximum threshold. As previously discussed, the receiving DNS nameserver can then utilize additional selection criteria to further prioritize or refine from potential POPs. For example, the receiving DNS nameserver can determine or obtain latency information related to an identified client computing device 102 (or corresponding DNS resolver component). In another example, the receiving DNS nameserver can associate a cost defined in terms of CDN server provider resources consumed and then select or prioritize POPs based on a minimization of the attributable CDN service provider costs. If no POPs in a selected tier have capacity, the receiving DNS nameserver can select one or more POPs that would otherwise be associated with a different, non-selected tier. For example, the receiving DNS nameserver can mitigate the unavailability of POPs at a selected tier by selecting POPs associated with a tier associated with higher financial costs or associated with better performance metrics. Illustratively, the adoption of mitigation techniques may not result in a higher financial cost to the content provider 104. At block 614, the receiving DNS nameserver resolves the DNS query by identifying the IP addresses of one or more of the selected POPs. At block 616, the routine 600 terminates.

While illustrative embodiments have been disclosed and discussed, one skilled in the relevant art will appreciate that additional or alternative embodiments may be implemented within the spirit and scope of the present invention. Additionally, although many embodiments have been indicated as illustrative, one skilled in the relevant art will appreciate that the illustrative embodiments do not need to be combined or implemented together. As such, some illustrative embodiments do not need to be utilized or implemented in accordance with scope of variations to the present disclosure.

Conditional language, such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment.

Any process descriptions, elements, or blocks in the flow diagrams described herein and/or depicted in the attached figures should be understood as potentially representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps in the process. Alternate implementations are included within the scope of the embodiments described herein in which elements or functions may be deleted, executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those skilled in the art. It will further be appreciated that the data and/or components described above may be stored on a computer-readable medium and loaded into memory of the computing device using a drive mechanism associated with a computer readable storing the computer executable components such as a CD-ROM, DVD-ROM, or network interface further, the component and/or data can be included in a single device or distributed in any manner. Accordingly, general purpose computing devices may be configured to implement the processes, algorithms and methodology of the present disclosure with the processing and/or execution of the various data and/or components described above.

It should be emphasized that many variations and modifications may be made to the above-described embodiments, the elements of which are to be understood as being among other acceptable examples. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims. 

What is claimed is:
 1. A computer-implemented method for request routing comprising: obtaining a DNS query from a client computing device, wherein the DNS query corresponds to a requested resource associated with a resource identifier, the requested resource provided by a content provider to a service provider; identifying one or more sets of POPs associated with the service provider based on prioritization information selected by the content provider; determining whether one or more POPs in the identified POPs can service additional content requests based on availability information associated with the one or more POPs; and transmitting information responsive to the DNS query based on the determination that one or more POPs have capacity.
 2. The method as recited in claim 1, wherein the resource identifier includes a unique content provider identifier accessible during DNS query processing.
 3. The method as recited in claim 1, wherein the sets of POPs are organized into two or more tiers of POPS and wherein identifying one or more sets of POPs based on the prioritization information includes identifying a selection of at least one tier of two or more tiers of POPs.
 4. The method as recited in claim 3, wherein the two or more tiers of POPs include at least one common POP in the two or more tiers.
 5. The method as recited in claim 3, wherein the two or more tiers of POPs include no common POP in the two or more tiers.
 6. The method as recited in claim 1, wherein the availability information includes historical information related to average POP capacity for processing resource requests.
 7. The method as recited in claim 6, wherein the historical information is associated with time criteria.
 8. The method as recited in claim 1, wherein the availability information includes real time measurements of POP capacity for processing resource requests.
 9. The method as recited in claim 1, wherein the availability information is based on a determined peak POP capacity for processing resource requests.
 10. The method as recited in claim 1, wherein the availability information is based on a determined health of one or more POPs.
 11. The method as recited in claim 1, wherein determining whether the one or more POPs can service additional content requests based on the availability information includes processing the availability information to determine POP capacity.
 12. The method as recited in claim 11, wherein processing the availability information includes associating an average characteristic of content requests associated with the content provider.
 13. The method as recited in claim 11, wherein processing the availability information includes associating a specified characteristic of content requests associated with the content provider.
 14. The method as recited in claim 13, wherein the specified characteristic corresponds to a specification of one of two or more specified size of requests.
 15. The method as recited in claim 11, wherein processing the availability information includes associating an average characteristic of content requests associated with a client computing device.
 16. The method as recited in claim 1 further comprising identifying one or more alternative POPs based on a determination that one or more POPs do have capacity.
 17. The method as recited in claim 1 further comprising determining one or more resource cache components that are configured to provide request content.
 18. A system for processing resource requests comprising: a DNS query processing component, executed on a computing device having process resources, the DNS query processing component operable to: obtain a DNS query from a client computing device, wherein the DNS query corresponds to a requested resource associated with a resource identifier, the requested resource provided by a content provider to a service provider; identify one or more sets of POPs associated with the service provider, the identification of the one or more sets of POPs based on prioritization information selected by the content provider; determine whether the one or more POPs in the identified set of POPs have capacity to service additional content requests based on availability information associated with the one or more POPs; and transmit information responsive to the DNS query based on the determination of that one or more POPs have capacity.
 19. The system as recite in claim 18, wherein the resource identifier includes a unique content provider identifier accessible during DNS query processing.
 20. The system as recite in claim 18, wherein identifying one or more sets of POPs based on the prioritization information includes identifying a selection from two or more tiers of POPs.
 21. The system as recited in claim 20, wherein the two or more tiers of POPs include at least one overlapping POP in the two or more tiers.
 22. The system as recited in claim 20, wherein the two or more tiers of POPs include no overlapping POP in the two or more tiers.
 23. The system as recited in claim 18, wherein the load information is based on historical information relate to average POP capacity for processing resource requests.
 24. The system as recited in claim 18, wherein the load information is based on a peak POP capacity for processing resource requests.
 25. The system as recited in claim 18, wherein determining whether the one or more POPs have capacity to service additional content requests based on the availability information includes processing the availability information to determine POP capacity.
 26. The system as recited in claim 25, wherein processing the availability information includes associating an average characteristic of content requests associated with at least one of the content provider or client computing device.
 27. The system as recited in claim 18, wherein the DNS query processing component is hosted at two or more POPs.
 28. The system as recited in claim 18, wherein the DNS query processing component is hosted independent of the two or more POPs. 